Did you catch what he was saying about people asking why the OT portrays a God of judgement? Paul pointed out how He dealt with the Philistines in grace by the way He revealed Himself to them even though they didn't get it.
When the ark was returned and those Israelis died after looking inside it, Pastor Paul pointed out that it was the law (the stone tablets) that was inside the ark. Those who died did so because they looked upon God by the law without the mercy seat.
Yes, God is holy but He has shown great grace by sending His Son. I think that sermon did an excellent job of contrasting people's perception of God in the OT as being vengeful, aka, a "Moral Monster", with the balanced picture of Him as a holy yet merciful God. The problem doesn't lie with God Himself being vengeful, it lies with sinful people who won't throw themselves on His mercy.
